Application Ser. No. 834,655 discloses a combination skid and valve seat for a bottom operable tank car lading valve modified for attachment by retrofit to the existing universal flange in railway tank cars.
Openings in the upper surface of the universal flange used primarily to hold a bottom outlet valve in place are provided with a filler. The universal flange includes a slot at its inner end on the inside of the tank. A ring is welded into this slot to support the upper end of the valve seat for the lading valve. Slots are provided in the internal surface of the combination skid and valve seat, and a retainer having outwardly extending circumferential projections extends into the slots. The retainer maintains a lading valve operator vertically fixed and spaced from the walls of the valve seat. First fasteners maintain the combination skid and valve seat attached to the universal flange. Second fasteners constituting a shear plane maintain a depending discharge outlet in engagement with the combination skid and valve seat.